biologia - Studia

STRUCTURE AND DYNAMICS OF THE PREDATOR MITE’S POPULATIONS IN SHRUBS ECOSYSTEMS
Soil samples were collected randomly. Ten samples from these areas were
collected with MacFadyen soil core (5 cm diameter), up to 10 cm deep, on three
layers: litter and fermentation (L),humus (S 1 ), soil (S 2 ). The extraction was
performed with a modified Berlese-Tullgren extractor, in ethylic alcohol and the
mite samples were clarified in lactic acid. The identification of the mites from the
Mesostigmata order was carried out to the species level (Gilarov and Bregetova,
1977; Hyatt, 1980; Karg, 1993; Masan and Fenda, 2004).
The statistical analysis was performed with MS Office Excel 2007. The
parameters studied were numerical density (no.indiviuals/sq.m.), relative abundance
(A%) and Shannon- Wiener diversity index (HS).
The humidity of soil was measured (Table 1).
Average of relative humidity of soil (%) recorded in 2006.
Table 1.
Soil level
(cm)
Cornu Nistoreşti Lunca Mare
0-10 27.38 ± 1.42 22.56 ± 5.94 34.44 ± 1.32
10-20 19.13 ± 7.61 22.39 ± 5.72 19.05 ± 1.11
20-30 20.21 ± 2.15 18.13 ± 6.18 12.61 ± 2.36
30-40 22.28 ± 0.28 20.52 ± 8.12 18.44 ± 0.89
Average 22.25 ± 0.94 20.98 ± 6.49 21.14 ± 0.21
Results and Discussions
The identification of collected material revealed the presence of 29 species
of predatory mites (Acari: Mesostigmata) belonging to the following families:
Parasitidae, Veigaidae, Rhodacaridae, Macrochelidae, Pachylaelaptidae,
Laelaptidae, Eviphididae, Zerconidae, Trachytidae, Uropodidae. The highest
species number was recorded at Nistoreşti (17 species), while the other sites had
lower species numbers (Cornu -15 species, Lunca Mare -13 species). The common
species identified for the three ecosystems were: Lysigamasus lapponicus, Veigaia
nemorensis, Zercon triangularis, Trachytes aegrota and Uropoda sp. (Table 2).
Making a comparative analysis of the annual numerical densities from the
studied ecosystem, we can remark that the most increased values were recorded at
Cornu and Nistoreşti (7900 ind./sq.m. and 7800 ind./sq.m.) and at Lunca Mare the
most decreased value (6400 ind./sq.m.). In temporal dynamics, a comparison of
this parameter showed that at Lunca Mare, the lowest values were obtained in May
and the highest in August.
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